Influence of the Incidence Angle of Sputtered Particles on the Surface, Interface, and Magnetic Properties of Fe/Si Multilayers Deposited by DC Magnetron Sputtering Technique with Large-Area Rectangular-Target

Fe/Si multilayer are widely used in polarized-neutron applications because of their high theoretical polarization efficiency. Reducing interface roughness is critical for maintaining the polarization performance of Fe/Si multilayers. In this paper, the honeycomb mask was designed to limit large-angle incident particles during the large-area rectangular-target direct current magnetron sputtering for lower interface and surface roughness of Fe/Si multilayers. The surface and interface performance were charactered with grazing incidence X-ray reflectivity, X-ray diffuse scattering, atomic force microscope and optical profilometer (OP). Hysteresis loop was measured to characterize the magnetic properties. The Fe-on-Si/Si-on-Fe interface widths decreased from 0.79/0.58 nm to 0.53/0.45 nm according to fitted Grazing incidence X-ray reflectivity (GIXR) curves. The surface roughness was reduced from 0.29/0.67 nm RMS in AFM/OP to 0.16/0.39 nm. The Fe-on-Si/Si-on-Fe interface roughness decreased from 0.71/0.50 nm to 0.47/0.40 nm according to fitted X-ray diffuse scattering (XRS) curves. The coercivity decreased from 50 Oe to 25 Oe in hysteresis loop results. These results indicate that limiting large-angle incident particles can reduce the coercivity by improving the interface and surface quality without changing the crystallite size These results indicate that limiting large-angle incident particles can reduce the coercivity by improving the interface and surface quality without changing the crystallite size